Global climate change is having a direct impact on the Earth's sea level and a group of scientists led by two University of Toronto geophysicists is providing the sea level "fingerprints" of polar ice sheet melting to prove it.

Share This

Global climate change is having a direct impact on the Earth's sea level and a group of scientists led by two University of Toronto geophysicists is providing the sea level "fingerprints" of polar ice sheet melting to prove it.

Related Articles

Rates of sea level change over the last century vary widely from one geographic location to another even after these rates have been corrected for known effects. The question has always been, why? What is causing these significant variations? Jerry Mitrovica, University of Toronto geophysics professor, is lead author of a paper to appear in the Feb. 22 issue of Nature that claims to have discovered the answer. And it is an answer that has an important impact on the debate over global climate change.

Mitrovica and his colleagues argue that scientists have not widely appreciated that melting from the Antarctic, for example, will have a distinctly different pattern or fingerprint in how it affects sea level than melting from Greenland or small mountain glaciers. It is these patterns that are causing the variation in the global sea level rise.

"We calculated these fingerprints using computer models and then showed that the observed record of sea level change displays the fingerprints," says Mitrovica. "Sea level is rising, and based on our work and the analysis of sea level data, not only can we assess the total amount melting from the ice caps, but we can also tell where that meltwater is coming from."

Mitrovica conducted this research with Mark Tamisiea, a University of Toronto post-doctoral fellow and second author on the paper, James Davis of the Harvard-Smithsonian Center for Astrophysics, and Glenn Milne of the University of Durham.

"In the past, people have been puzzled by the significant variations in sea levels in different parts of the world," says Mitrovica. "Like throwing water in a bathtub, many scientists assumed that if polar ice melting were contributing to sea level rise, it would present itself evenly and uniformly across the Earth's oceans."

And that assumption, he says, is simply wrong.

Mitrovica uses Greenland as an example. It was assumed that if the ice caps on Greenland were melting, all coastal locations would flood evenly.

"In fact," he continues, "if the entire Greenland ice cap melted, then places relatively close by, like Britain and Newfoundland, would actually see sea levels fall. The reason is fairly simple: despite its small size, the Greenland ice sheet exerts a strong gravitational pull on the seas. As the polar sheet melts, it will exert less pull, resulting in lower - not higher - sea levels around Greenland. Of course, sea levels will rise on average, and as the meltwater moves away from Greenland it will create problems for countries in the Southern Hemisphere. In the same way, melting from the Antarctic will raise sea levels in the Northern Hemisphere, but not in places like Australia."

To look for evidence of their ideas, the scientists re-examined the data from tide gauges that measure sea levels. The results startled even them. They found that they could fit nearly all the geographic variations in sea level that they saw in these tide gauges using the distinct sea level patterns they predicted for the melting of polar ice sheets. It is estimated that sea levels are rising, on average, by about 1.8 millimetres per year.

"We've really strengthened the link between today's sea level changes and ice melting and we've found a way of unraveling the details of this link. By doing that, we've also strengthened extrapolations being made for the future effect of climate warming. And these extrapolations show continued acceleration of sea level rise late into the present century, leading to more flooding of coastal communities."

This study was funded by the Ontario Premier's Research Excellence Award program, the Canadian Institute for Advanced Research and the Natural Sciences and Engineering Research Council of Canada.

University Of Toronto. (2001, February 22). "Fingerprints" Of Melting Ice Caps Point Directly To Global Climate Change And Sea Level Rise. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2001/02/010222075413.htm

More From ScienceDaily

More Earth & Climate News

Featured Research

Mar. 31, 2015 — The ocean is a large reservoir of dissolved organic molecules, and many of these molecules are stable against microbial utilization for hundreds to thousands of years. They contain a similar amount ... full story

Mar. 31, 2015 — Using the assessment tool ForWarn, US Forest Service researchers can monitor the growth and development of vegetation that signals winter's end and the awakening of a new growing season. Now these ... full story

Mar. 31, 2015 — Geoscientists have revealed information about how continents were generated on Earth more than 2.5 billion years ago -- and how those processes have continued within the last 70 million years to ... full story

Mar. 31, 2015 — Until now electric fences and trenches have proved to be the most effective way of protecting farms and villages from night time raids by hungry elephants. But researchers think they may have come up ... full story

Mar. 31, 2015 — The volcanologist Stephen Self, an expert on super-eruptions, was the first modern-day scientist to visit Tambora in Indonesia, the site of the largest volcanic eruption in 1,000 years. On the 200th ... full story

Mar. 31, 2015 — Researchers have detected a human fingerprint deep in the Borneo rainforest in Southeast Asia. Cold winds blowing from the north carry industrial pollutants from East Asia to the equator, with ... full story

Mar. 31, 2015 — Landfills can make a profit from all their rotting waste and a new patent explains exactly how to make the most out of the stinky garbage sites. Decomposing trash produces methane, a landfill gas ... full story

Mar. 31, 2015 — As the five-year anniversary of the explosion of the Deepwater Horizon oil rig approaches, a new report looks at how twenty species of wildlife are faring in the aftermath of the ... full story

Mar. 31, 2015 — Scientists have discovered why the first buds of spring come increasingly earlier as the climate changes. As the climate changes the sweet spot for seeds comes earlier in the year, so first flowers ... full story

Mar. 31, 2015 — In the 1990s the discovery of the oldest human made and completely preserved wooden hunting weapons made the Paleolithic excavation site in Schoningen internationally renowned. Contained within the ... full story

Related Stories

Jan. 20, 2015 — Melting of glacial ice will probably raise sea level around the globe, but how fast this melting will happen is uncertain. In the case of the Greenland Ice Sheet, the more temperatures increase, the ... full story

Jan. 8, 2015 — The balmy islands of Seychelles couldn't feel farther from Antarctica, but their fossil corals could reveal much about the fate of polar ice sheets. About 125,000 years ago, the average global ... full story

Mar. 18, 2013 — Glaciers at the edge of Greenland which are not connected to its huge ice sheet, or can be clearly separated from it, are contributing to sea-level rise much more than previously thought. Scientists ... full story

Apr. 24, 2012 — As the Earth's climate warms, a melting ice sheet produces a distinct pattern of sea level change known as its sea level fingerprint. Now, geophysicists have found a way to identify the sea ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.